626 
SESAMOID LAMENESS. 
inflammation. (For the anatomy of the parts, see figs. 221 and 222, 
p. 595.) Brauell, in 1845, first drew attention to inflammation of the 
posterior surface, and pointed out that it was similar in character to 
that of chronic navicular disease. Ten years later Mascher described 
the disease, for which Gunther introduced the name sesamoid lameness. 
Schrader afterwards gave a thorough pathological and anatomical 
description of it. Acute inflammation of the 
posterior gliding surface of the sesamoid 
bones sometimes occurs in consequence of 
acute tendovaginitis of the flexor apparatus. 
James states having found an abscess about the 
size of a walnut (?) in the sesamoid bones (?) of a 
draught-horse. It was supposed to have been 
caused by injury, and was accompanied by acute 
inflammation of the tendon sheaths. Probably 
the condition was purulent tendovaginitis. In 
two horses treated for local gangrene of the skin 
of the hindlimbs, suppuration occurred in the 
perforans tendon sheath, with rupture of the 
flexor tendon. Post-mortem examination showed 
necrosis of the tendon, of the posterior surface 
of the sesamoid bones, and of the navicular bone. 
The process had extended downwards in the 
track of the tendons, and had attacked the navi¬ 
cular bursa. From a clinical standpoint such 
acute inflammation is of less importance than the 
chronic processes (identical in character with 
navicular disease), i.e., which consist of an 
arthritis chronica, and which at times are com¬ 
plicated with disease of the sheath of the flexor 
pedis perforans just above the fetlock. 
Pathological anatomy. Changes charac¬ 
teristic of arthritis chronica are found affecting 
the gliding surface of one or other of the sesa¬ 
moid bones; the cartilage becomes eroded, and 
Fig. 244.—The flexor pedis per- margins proliferate. When the anterior surface 
forans and perforatus tendons is diseased, both it and the posterior articulatory 
in a case of sesamoid lame- surface of the metacarpus exhibit abraded and 
ness; at the point where it eroded spots. In disease of the posterior surface 
the perforans tendon is fibril- °* ^he sesamoid bones, the flexor tendons appear 
lated (after Brauell). fibrillated (fig. 244), or are sometimes completely 
ruptured. Brauell saw a few cases of adhesion of 
the flexor tendons to the sesamoid bones. The sides of the bone show osseous 
deposits. The tendon sheaths and sesamoid ligaments are also thickened; 
sometimes detached pieces of bone are found in the sheath. In the cases 
reported by Levens, the sesamoid bones had probably been fractured. 
As a rule, both sesamoid bones are affected ; Mascher, however, in some 
cases found disease of a single sesamoid and of the corresponding metacarpal 
articular surface. 
Causes. Any violent strain of the flexor apparatus or increase of the 
pressure normally exerted by the flexor tendons on the sesamoid bones 
